We are developing a system of biochemical markers for Epstein-Barr virus (EBV), since a genetic system has never been developed for this human herpes virus. In this way we plan to study early events in the course of viral infection of both the abortive lytic and transforming types. We have isolated two EBV-associated DNA polymerase activities, one of which is intracellular and related to viral production, and the other of which is virion-associated. An intracellular nuclease has also been isolated. We propose to further purify these enzymes and to investigate their biological functions by 1) further in vitro studies using various forms of viral DNA as template or substrate, 2) generation of specific antisera in mice in order to study enzyme complex formation between nuclease and polymerase, 3) investigating the existence of further virus related enzymes such as a virion-associated nuclease. We propose to match these studies of viral enzymes with studies of EBV DNA synthesis, using EBV superinfected cells as a source of newly replicated viral DNA intermediates. We also propose to use inhibitors of herpes virus DNA synthesis such as adenine arabinoside and phosphonoacetic acid as aides in studies of EBV DNA replicative intermediates and the viral enzymes which generate them.